Embodiments of the present disclosure relate to the field of liquid crystal display, and particularly to a gate drive method and a gate drive device of a liquid crystal display.
Recently, the liquid crystal display (LCD) related products have been developed rapidly. More and more LCDs with high quality gradually come into the market, and the application fields thereof are increasingly broadened.
The basic principle of displaying images by a LCD is as follows. Different voltages are applied between the two electrode plates of the liquid crystal to deflect the liquid crystal molecules by a certain angle, so that the light can pass through. The transmission ratio of the liquid crystal is determined by the deflection angle of the liquid crystal molecules. Thereby, a gradation display with different grayscales is generated.
Usually, in order to prevent the liquid crystal molecules from aging, a polarity reversion is used when images are displayed by the LCD. The polarity in the “polarity reversion” is referred to as a positive polarity when the pixel voltage is higher than the voltage of the common electrode signal, and referred to as a negative polarity when the pixel voltage is lower than the voltage of the common electrode signal. Due to factors such as parasitic capacitance, the actual pixel voltage of the pixel electrode is inconsistent with the data line voltage, and there is a voltage difference ΔVp. Due to the existence of ΔVp and the requirement for polarity reversion between the positive polarity and the negative polarity, the common electrode signal Vcom is required to be in the center between the positive polarity and the negative polarity.
Usually, at the development stage as well as the mass production stage, the common electrode signal Vcom is adjusted to be in the center between the positive polarity and the negative polarity of the actual pixel electrode, then applied to the product. In the prior art, generally, either ΔVp is reduced by reducing the parasitic capacitance, or the common electrode signal Vcom is adjusted by using a feedback loop. However, the inventor finds out that there are at least the following problems in the prior art. Firstly, in the method of reducing ΔVp by reducing the parasitic capacitance, due to restrictions on the charge and discharge requirements, ΔVp is reduced in a limited extent, and adjustment effect is unsatisfactory. Secondly, in the method of adjusting the common electrode signal Vcom by using the feedback loop, since a decision depending on the visual sense of the operator is needed, the adjusted common electrode signal Vcom may not be exact in the center between the positive polarity and the negative polarity of the actual pixel electrode. Therefore, the adjustment effects of the two methods are both unsatisfactory, and the two methods cannot resolve the flickering caused by the voltage difference ΔVp and the residual image caused by the residual direct current.